Treatment of cellulose derivatives.



FRANZ STEIMMIG, OF'HANOVER', GERMANY.

' TREATMENT OF CELLULOSE DERIVATIVES.

No Drawing.

To all whom it may concern:

Be 1t known that I, FRANZ STEIMMIG,

citizen of the German Empire, residing at Hanover, Germany, have invented certain new and useful Improvements in the-Treatment of Cellulose Derivatives, of which the following is a specification.

This invention relates to the production of cellulose compounds for the manufacture of films or filaments for fabrics out of the material known commercially as viscose which is produced from a solution of cellulose as described'in U. S. Patent No. 520770 dated June 5th, 1894. In the manufacture of fabrics from viscose however, preference has been given to acidulated solutions for setting purposes, This is readily understood in view of the fact that viscose contains acellulose derivative which is soluble in an alkaline solution, that is to say, it cannot be acted upon by the alkali to bring it into an insoluble state. Nevertheless it would be advantageous to employ a setting bath with an alkaline action for cellulose derivatives produced from viscose. It is known that'viscose may be coagulated by the aid of. a concentrated solution of a neutral salt (Patent No. 520770 of 1894). This coagulating action cannot however be employed commercially'in a satisfactory manner to produce derivatives of cellulose'with continuous operation of the process owing to the fact that the increasing quantity of alkali in-the bath soon renders its presence felt by preventing the coagulation. I have discovered that an excellent setting bath may be made with a solvent of such neutral salts by adding a certain quantity of an ammonium salt to the same, for instance ammonium sulfate. Excellent results have been obtained with a precipitating bath made with a concentrated solution of common salt (sodium chlorid) to which about 10% of ammonium sulfate is added. This result is somewhat unexpected as in view of the experiencegained with the process described in U. S. Patent No. 622087 dated 28th March, 1899, it would appear that only a concentrated solution (say 30% to-40%) of ammonium sulfate would provide an effective setting bath, that is to say a solution containing about three to four times as muchammonium sulfate as the solution mentioned above. It should also be remembered that it is impossible with ordinary commercial viscose to precipitate a single filament with Specification of Letters Patent.

Patented Oct. 10, 1916.

' Application filed June 12, 1913. Serial No. 773,324.,

a ten per cent. ordinary monium sulfate.

The followingnumerical examples will serve to illustrate the present invention: 20

solution of amkg. of common salt, 10 kg. of ammonium sulfate, 70 kg. of water or kg. of Glauber salts, 10 kg. of ammonium sulfate, 30 kg.

of water. The bath is kept at about 35 C. to 40 C. in order to retain this large quantlty of salt in solution.

A bath such as described is much cheaper than that described in Patent No. 622087 of 1899, so that it may compete commercially with the acidulatedbaths.)

The quantity of ammonium salt to be added to the neutral salt solution such as brine may be varied within narrow limits only. The amount depends to a great extent upon the kind of product which it is desired to produce. The best amount to add should be found by trial in every case, but it should be retained as low as possible in the interests of cheapness. The best neutral salt for any given purpose must also be tried out, choice being made from common salt, Glauber salts, chlorid of magnesium or calcium chlorid. In some cases an organic substance such as glycerin or other compound or tertiary alcohol may also be added.

It is preferable to use in conjunction with my improved precipitating bath some third substance, such as reducing agents or sodium hypochlorite which have the effect of improving the fibers. It is also quite practical to add metal salts to the precipitating bath as is known in another process, which salts form insoluble sulfids with the alkawhereupon they are preferably suitably fixed in acid and washed in water and finally dried. The further treatment of the filaments or films proceeds in the .usual manner.

The process not only results in greater economy in the manufacture of artificial silk, but also produces a product which is materially stronger and tougher, than any of the threads heretofore produced from viscose, by precipitation in a non-acid bath.

One objection to the non-acid bath heretofore proposed, such as a saturated solution of ammonium sulfate, or a saturated solution of sodium chlorid, is that the thread produced thereby is very much weaker than the thread produced by the acid-baths'heretofore employed, but the present process fully overcomes this objection.

I claim': 4

1. A setting bath for producing articles a from viscose and the like, which comprises an ammonium salt.

an acid-free, concentrated solution of a neutral salt, containing a small amount of an ammonium salt. a

2. A setting bath for producing articles from viscose and the like, which comprises an acid-free, concentrated solution of sodium chlorid, containing a small amount of 3. A setting bath i or producing articles from viscose and the like, which comprises cent. of ammonium sulfate.

5. A setting bath for producing articles from viscose and the like,- which comprises an acid free, concentrated solution of sodium chlorid, containing ammonium sulfate.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

DB. Inc. FRANZ STEIMMIG.

Witnesses:

WILHELM BRooKHAUsER, QOTTILIE Tm'rz. 

